Tachometer

[Andy J]

Need to buy myself a tachometer for use with various size IC engines (all using 2 blade props) and see that there a numerous listings on ebay for one marked with a brand name G.T. Power Rc for around £20. Anybody recommend these or should I be looking at another manufacturer.

[EarlyBird]

 

Servo Shop

 

 

[Andy J]

Does the above product perform better than other makes?

[Paul De Tourtoulon]

I have had a few they seem to all be the same, working on the same principal the one you show I had trouble

 after a while of it eating up battery's, I now use a 30 year old one with it's PP9 battery.

[GrumpyGnome]

I've never used mine - it just sits, forgotten, in it's nice little draw-string bag, at the bottom if my field box......

[Paul De Tourtoulon]

Just now, GrumpyGnome said:

I've never used mine - it just sits, forgotten, in it's nice little draw-string bag, at the bottom if my field box......

Send it to Andy,,,,

[Nigel Heather]

1 hour ago, GrumpyGnome said:

I've never used mine - it just sits, forgotten, in it's nice little draw-string bag, at the bottom if my field box......

Same, I’ve got one that is probably 15 years or more old.  I got it when I first got into the hobby with IC powered aircraft - I read about them and assumed that they were a essential part of tuning the engine so, because I could afford one, I bought one.

 

Other than a few plays to see if it worked (it seemed to), I don’t think I ever used it.  I came across it earlier this year, lying forgotten in a drawer, I powered it up, original battery still working, and tested it, seemed to work fine.  Put it back in the drawer, to be forgotten and re-discovered in the distant future.

Edited December 6, 2022 by Nigel Heather

[EarlyBird]

I bought mine at the same time as I bought a ~£500 engine and knowing nothing about IC I read the manual in which rpm were given.

 

As can be seen from my photo above this has a JP badge. My thoughts are that they are all the same or, cloned, copied or badged. I have no proof of this but at £20 I have better things to think about. I have used it to check the rpm during running in the engine. At the field I have never seen one used, not that I have ever looked for one.

 

Steve

[Ron Gray]

I used to have one like Steve has shown but got fed up with it switching itself on when it was in the toolbox (on/off switch on the side) so I now use one like this. Useful when comparing rpm of different props.

 

Edited December 6, 2022 by Ron Gray

[EarlyBird]

1 minute ago, Ron Gray said:

I used to have one like Steve has shown but got fed up with it switching itself on when it was in the toolbox (on/off switch on the side)

I wondered why the battery went flat, thanks Ron.

 

Steve

[Jon H]

I use the type Ron pictured. Very good and handy for checking stuff. 

 

They are however useless as a tuning aid so dont bother trying to use them for that purpose. For comparing prop A to prop B, for checking your engine vs a known benchmark, for setting idle rpm etc they are very useful. 

[J D 8]

             I have much the same story as Nigel above. 

If you do purchase one do not use under artificial light like I did running IC in the garage with door open. Caused much confusion

[Andy J]

So which makes use a Pp3 battery?

 

[Ron Gray]

 Click on the photo in my post above and it will go to a website (RC World - there are others who also stock similar ones).

[kc]

That link to RC World has lots of unusual things under Handy Items- things you didn't know you needed until you saw them   - Workbench Tx stand or Bench buddy Organiser.    One really essential item would be the 5 prong pickup tool - I have a 3 prong version and it's so handy for inserting servo screws etc. 

[Trevor]

5 hours ago, Jon - Laser Engines said:

I use the type Ron pictured. Very good and handy for checking stuff. 

 

They are however useless as a tuning aid so dont bother trying to use them for that purpose. For comparing prop A to prop B, for checking your engine vs a known benchmark, for setting idle rpm etc they are very useful. 

And also helpful on multi-engined aircraft.

[Jon H]

8 minutes ago, Trevor said:

And also helpful on multi-engined aircraft.

 

Not really. The tach is not as accurate as your ears and its easy to tell when the engines are in sync. The engines will also unload and rev slightly differently when in the air so ground measurement is not that helpful. Not that it matters, reliability is more important than having the engines perfectly together. 

[john stones 1 - Moderator]

A tacho can be a troublesome tool in some hands, it can turn a flyer into an obsessive who'll tweak the needle all day coz book says ..... rpm, we have a couple of em at our club, they're a pain in the rear drowning out all conversation.

 

On tachoing props, can a prop that flies the model less well than another brand, give good rpm numbers on the floor ? Thus giving a false impression, or do the less efficient ones for flying give poor rpm numbers as well ?

[J D 8]

   More likely the poor prop will give more revs on the tacko than the better prop which is moving air, which after all is the name of the game.

[Jon H]

1 hour ago, john stones 1 - Moderator said:

A tacho can be a troublesome tool in some hands, it can turn a flyer into an obsessive who'll tweak the needle all day coz book says ..... rpm, we have a couple of em at our club, they're a pain in the rear drowning out all conversation.

 

On tachoing props, can a prop that flies the model less well than another brand, give good rpm numbers on the floor ? Thus giving a false impression, or do the less efficient ones for flying give poor rpm numbers as well ?

 

37 minutes ago, J D 8 said:

   More likely the poor prop will give more revs on the tacko than the better prop which is moving air, which after all is the name of the game.

 

 

Both of these statements are right on the money. Rev chasing with tacho's is a real problem and rpm is not thrust. 

 

When it comes to manufacturers benchmark RPM's on a given prop assume +-200 margin on the figure they give to cover things like weather conditions, temperature etc. Screwing the life out of your needle because you had 8500rpm yesterday and only 8400 today is not the way to do it.

[i12fly]

I've had 2 similar to Earlybirds picture. Disappointingly poor. First ate batteries so protected the switch so it couldn't switch on accidentally  -still ate batteries even when switched off but after a year left idle the switch packed up, couldn't mend it so threw it away.

Second one was different brand, more expensive but very similar, switch is protected by design but it eats batteries when switched off. Probably still works though, keep meaning to look it out one day and try it.

[Paul De Tourtoulon]

my first one was the Thunder tiger one, a must with ducted fans,,

 the second one which should shut itself off automatically ate battery's like they were out of fashion,

the third one museum piece, which was very helpful when I was fiddling with different carburateurs and inlet

pipes and set ups on my Enya 120 4c not forgetting re ringing engines and trying different fuels and plugs.

 

You can always dazzle the beginners 😆

and also your field credibility just leaving it on show on the top of your field box,

it can also stir up a good conversation,or  just put it next to a bottle of castor oil,,,🥳

Edited December 6, 2022 by Paul De Tourtoulon
forgot photos, carried away,,,

[Andy J]

4 hours ago, Ron Gray said:

 Click on the photo in my post above and it will go to a website (RC World - there are others who also stock similar ones).

Not particularly cheap by the time they add postage, but at least they had one in stock.

 

[Ron Gray]

Looks like they no longer do! Nexus have one.

[Andy J]

Well impressed that the RC World stock control works. Item should be on its way to me today.